1. Field of the Invention
This invention relates to a magnetic tape contact printing apparatus for transferring information signals recorded on a mother tape to a copy tape. More particularly, it relates to a magnetic tape contact printing apparatus in which rotation of two pairs of reels about which the mother tape and the copy tape are respectively wound is controlled by a controller on the basis of rotational acceleration of a rotational transfer drum adapted to drive the tapes, so that the tension applied to the tapes at the time of starting and stopping of rotation of the rotational transfer drum is maintained at a predetermined value.
2. Description of the Prior Art
There has been proposed a magnetic tape contact printing apparatus in which the copy tape is brought into intimate contact with the mother tape for transferring information signals recorded on the mother tape to the copy tape.
In such magnetic tape contact printing apparatus, the mother tape is wound on a mother tape supply reel and taken up from this mother tape supply reel on a mother tape take-up reel by way of a contact printing section. The copy tape is wound on a copy tape supply reel and taken up from this copy tape supply reel on a copy tape take-up reel by way of the contact printing section.
The contact printing section has a transfer bias head and a rotational transfer drum, and the two tapes are adapted to run between the bias head and the drum in an overlapping relation to each other. Thus, in this contact printing section, the mother tape and the copy tape are brought into intimate contact with each other. During contact printing, these tapes are driven by rotation of the rotational transfer drum, and an A.C. bias magnetic field of a predetermined frequency is applied to the tapes by the transfer bias head. The information signals are transferred in this manner from the mother tape onto the copy tape.
In the above described magnetic tape contact printing apparatus, a tension servo control system is included for preventing tape destruction, such as tape breakage, caused by the increase in tension of the mother tape and the copy tape. This control system operates in such a manner that the tension applied to the tapes is sensed and the driving or braking of the reels about which the tapes are wound is controlled by a controller on the basis of the sensed results.
In the operation of the tension servo control system, there have been proposed, as means for applying tension to the tapes and sensing such tension, means including tension arms supported for rotation and biased to be turned in a predetermined direction and angular sensors for sensing the rotational positions of these tension arms.
For effecting high speed and efficient transfer of the information signals in the above described contact printing apparatus, it is necessary to accelerate or decelerate the transfer drum rapidly at the time of starting and stopping of transfer of the information signals.
However, when the transfer drum is accelerated or decelerated rapidly, each tape experiences rapid fluctuations in tape tension, so that there arises the risk that the tension sensors, such as the aforementioned tension arms, cannot follow the changes in tape tension. When the tension sensors cannot follow the changes in tape tension, the tape tension cannot be maintained at a prescribed value but may be increased excessively to cause tape rupture. The copy tape is especially likely to be ruptured because it has less thickness and tensile strength than the mother tape.